sched_ext: Sub-allocator over kernel-claimed BPF arena pages

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Build a per-scheduler sub-allocator on top of pages claimed from the BPF
arena registered in the previous patch. Subsequent kernel-managed
arena-resident structures (e.g. per-CPU set_cmask cmask) carve their storage
from this pool.

scx_arena_pool_init() creates a gen_pool. scx_arena_alloc() returns the
kernel VA. On exhaustion, the pool grows by claiming more pages via
bpf_arena_alloc_pages_sleepable(). Chunks are added at the kernel-side
mapping address. Callers translate to the BPF-arena form themselves if
needed.

Allocations sleep (GFP_KERNEL) - they may grow the pool through vzalloc and
arena page allocation. All current consumers run from the enable path (after
ops.init() and the kernel-side arena auto-discovery, before validate_ops()),
where sleeping is fine.

scx_arena_pool_destroy() walks each chunk, returns outstanding ranges to the
gen_pool with gen_pool_free() and then calls gen_pool_destroy(). The
underlying arena pages are released when the arena map itself is torn down,
so the pool destroy doesn't free them explicitly.

v2: Switch scx_arena_alloc() to a loop. (Andrea)

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

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This commit is contained in:

Tejun Heo 2026-05-22 07:06:01 -10:00

parent 0e2819cba9

commit 9eca087deb

5 changed files with 164 additions and 0 deletions

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4

kernel/sched/build_policy.c

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11

kernel/sched/ext.c

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126

kernel/sched/ext_arena.c

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18

kernel/sched/ext_arena.h

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5

kernel/sched/ext_internal.h

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